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JOSE Working GroupM. Jones
Internet-DraftMicrosoft
Intended status: Standards TrackNovember 6, 2012
Expires: May 10, 2013 


JSON Web Encryption JSON Serialization (JWE-JS)
draft-jones-jose-jwe-json-serialization-03

Abstract

The JSON Web Encryption JSON Serialization (JWE-JS) is a means of representing encrypted content using JavaScript Object Notation (JSON) data structures. This specification describes a means of representing secured content as a JSON data object (as opposed to the JWE specification, which uses a compact serialization with a URL-safe representation). It enables the same content to be encrypted to multiple parties (unlike JWE). Cryptographic algorithms and identifiers used with this specification are described in the separate JSON Web Algorithms (JWA) specification. The JSON Serialization for related digital signature and MAC functionality is described in the separate JSON Web Signature JSON Serialization (JWS-JS) specification.

Status of this Memo

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This Internet-Draft will expire on May 10, 2013.

Copyright Notice

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Table of Contents

1.  Introduction
    1.1.  Notational Conventions
2.  Terminology
3.  JSON Serialization
4.  Example JWE-JS
5.  IANA Considerations
6.  Security Considerations
7.  References
    7.1.  Normative References
    7.2.  Informative References
Appendix A.  Acknowledgements
Appendix B.  Open Issues
Appendix C.  Document History
§  Author's Address




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1.  Introduction

The JSON Web Encryption JSON Serialization (JWE-JS) is a format for representing encrypted content as a JavaScript Object Notation (JSON) [RFC4627] (Crockford, D., “The application/json Media Type for JavaScript Object Notation (JSON),” July 2006.) object. It enables the same content to be encrypted to multiple parties (unlike JWE [JWE] (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” November 2012.).) The encryption mechanisms are independent of the type of content being encrypted. Cryptographic algorithms and identifiers used with this specification are described in the separate JSON Web Algorithms (JWA) [JWA] (Jones, M., “JSON Web Algorithms (JWA),” November 2012.) specification. The JSON Serialization for related digital signature and MAC functionality is described in the separate JSON Web Signature JSON Serialization (JWS-JS) [JWS‑JS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature JSON Serialization (JWS-JS),” November 2012.) specification.



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1.1.  Notational Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in Key words for use in RFCs to Indicate Requirement Levels [RFC2119] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).



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2.  Terminology

This specification uses the same terminology as the JSON Web Encryption (JWE) [JWE] (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” November 2012.) specification.



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3.  JSON Serialization

The JSON Serialization represents encrypted content as a JSON object with a recipients member containing an array of per-recipient information, an initialization_vector member containing a shared Encoded JWE Initialization Vector value, and a ciphertext member containing a shared Encoded JWE Ciphertext value. Each member of the recipients array is a JSON object with a header member containing an Encoded JWE Header value, an encrypted_key member containing an Encoded JWE Encrypted Key value, and an integrity_value member containing an Encoded JWE Integrity Value value.

Unlike the compact serialization used by JWEs, content using the JSON Serialization MAY be encrypted to more than one recipient. Each recipient requires:

Therefore, the syntax is:

  {"recipients":[
    {"header":"<header 1 contents>",
     "encrypted_key":"<encrypted key 1 contents>",
     "integrity_value":"<integrity value 1 contents>"},
    ...
    {"header":"<header N contents>",
     "encrypted_key":"<encrypted key N contents>",
     "integrity_value":"<integrity value N contents>"}],
   "initialization_vector":"<initialization vector contents>",
   "ciphertext":"<ciphertext contents>"
  }

The contents of the Encoded JWE Header, Encoded JWE Encrypted Key, Encoded JWE Initialization Vector, Encoded JWE Ciphertext, and Encoded JWE Integrity Value values are exactly as specified in JSON Web Encryption (JWE) [JWE] (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” November 2012.). They are interpreted and validated in the same manner, with each corresponding header, encrypted_key, and integrity_value value being created and validated together.

Each JWE Encrypted Key value and the corresponding JWE Integrity Value are computed using the parameters of the corresponding JWE Header value in the same manner described in the JWE specification. This has the desirable result that each Encoded JWE Encrypted Key value in the recipients array and each Encoded JWE Integrity Value in the same array element are identical to the values that would have been computed for the same parameters in a JWE, as is the shared JWE Ciphertext value.

All recipients use the same JWE Ciphertext and JWE Initialization Vector values, resulting in potentially significant space savings if the message is large. Therefore, all header parameters that specify the treatment of the JWE Ciphertext value MUST be the same for all recipients. This primarily means that the enc (encryption method) header parameter value in the JWE Header for each recipient MUST be the same.



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4.  Example JWE-JS

This section contains an example using the JWE JSON Serialization. This example demonstrates the capability for encrypting the same plaintext to multiple recipients.

Two recipients are present in this example: the first using the RSAES-PKCS1-V1_5 algorithm to encrypt the Content Master Key (CMK) and the second using RSAES OAEP to encrypt the CMK. The Plaintext is encrypted using the AES CBC algorithm and the same block encryption parameters to produce the common JWE Ciphertext value. The two Decoded JWE Header Segments used are:

  {"alg":"RSA1_5","enc":"A128CBC+HS256"}

and:

  {"alg":"RSA-OAEP","enc":"A128CBC+HS256"}

The keys used for the first recipient are the same as those in Appendix A.2 of [JWE] (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” November 2012.), as is the plaintext used. The asymmetric encryption key used for the second recipient is the same as that used in Appendix A.1 of [JWE] (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” November 2012.); the block encryption keys and parameters for the second recipient are the same as those for the first recipient (which must be the case, since the initialization vector and ciphertext are shared).

The complete JSON Web Encryption JSON Serialization (JWE-JS) for these values is as follows (with line breaks for display purposes only):

  {"recipients":[
    {"header":
      "eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0",
     "encrypted_key":
      "ZmnlqWgjXyqwjr7cXHys8F79anIUI6J2UWdAyRQEcGBU-KPHsePM910_RoTDG
       u1IW40Dn0dvcdVEjpJcPPNIbzWcMxDi131Ejeg-b8ViW5YX5oRdYdiR4gMSDD
       B3mbkInMNUFT-PK5CuZRnHB2rUK5fhPuF6XFqLLZCG5Q_rJm6Evex-XLcNQAJ
       Na1-6CIU12Wj3mPExxw9vbnsQDU7B4BfmhdyiflLA7Ae5ZGoVRl3A__yLPXxR
       jHFhpOeDp_adx8NyejF5cz9yDKULugNsDMdlHeJQOMGVLYaSZt3KP6aWNSqFA
       1PHDg-10ceuTEtq_vPE4-Gtev4N4K4Eudlj4Q",
     "integrity_value":
      "8LXqMd0JLGsxMaB5uoNaMpg7uUW_p40RlaZHCwMIyzk"},
    {"header":
      "eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkExMjhDQkMrSFMyNTYifQ",
     "encrypted_key":
      "nxwnYB86zEvVRofSxnDuFAE9-Gi2JtCy5eMyYedowjfGlkoA-Y0JyfwWXE_EU
       vhq6WS_DM3a18You2Qsah3BvvSRPZ8-TNYX3_4QCEO-V8EVbF1eGoJFs9ODmC
       cOiuMl1xLnSAYlwEDDnhwEkXv8o6MZEvh-msqTY6NyFGd6mhjpu9P4o2F2hOe
       Nt6FthcR4cNpAVSbydEEBszsrp27nB-JwfmLjnSYQO1JBwbgUJXHZyIJcQa7i
       43Vko02HkWTxBta0q5Zr_Jd7V2l-6HLYIuNc7fZH1DSJSTBTotcugumR5zNX_
       uxQyMoWOQ-SsQ7HxqrrFbo5FNoLPZiuNYuCdQ",
     "integrity_value":
      "QbYksTWNZTcMfJMLoGB_aTCA0-IuNObm19_VdpabviM"}],
   "initialization_vector":
    "AxY8DCtDaGlsbGljb3RoZQ",
   "ciphertext":
    "Rxsjg6PIExcmGSF7LnSEkDqWIKfAw1wZz2XpabV5PwQsolKwEauWYZNE9Q1hZJE
     Z"
  }


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5.  IANA Considerations

This specification makes no requests of IANA.



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6.  Security Considerations

The security considerations for this specification are the same as those for the JSON Web Encryption (JWE) [JWE] (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” November 2012.) specification.



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7.  References



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7.1. Normative References

[JWA] Jones, M., “JSON Web Algorithms (JWA),” November 2012.
[JWE] Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” November 2012.
[RFC2119] Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” BCP 14, RFC 2119, March 1997 (TXT, HTML, XML).
[RFC4627] Crockford, D., “The application/json Media Type for JavaScript Object Notation (JSON),” RFC 4627, July 2006 (TXT).


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7.2. Informative References

[I-D.rescorla-jsms] Rescorla, E. and J. Hildebrand, “JavaScript Message Security Format,” draft-rescorla-jsms-00 (work in progress), March 2011 (TXT).
[JSE] Bradley, J. and N. Sakimura (editor), “JSON Simple Encryption,” September 2010.
[JWS-JS] Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature JSON Serialization (JWS-JS),” November 2012.


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Appendix A.  Acknowledgements

JSON serializations for encrypted content were previously explored by JSON Simple Encryption (Bradley, J. and N. Sakimura (editor), “JSON Simple Encryption,” September 2010.) [JSE] and JavaScript Message Security Format (Rescorla, E. and J. Hildebrand, “JavaScript Message Security Format,” March 2011.) [I‑D.rescorla‑jsms].



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Appendix B.  Open Issues

[[ to be removed by the RFC editor before publication as an RFC ]]

The following items remain to be considered or done in this draft:



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Appendix C.  Document History

[[ to be removed by the RFC editor before publication as an RFC ]]

-03

-02

-01

-00

draft-jones-json-web-encryption-json-serialization-02

draft-jones-json-web-encryption-json-serialization-01

draft-jones-json-web-encryption-json-serialization-00



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Author's Address

  Michael B. Jones
  Microsoft
Email:  mbj@microsoft.com
URI:  http://self-issued.info/